COMPARISON OF THE HARTREE-FOCK, MOLLER-PLESSET, AND HARTREE-FOCK-SLATER METHOD WITH RESPECT TO ELECTROSTATIC PROPERTIES OF SMALL MOLECULES - EFFECTS OF ELECTRON CORRELATION

The results of various quantum chemical calculations, the Hartree-Fock (HF) method, the Moller-Plesset perturbation theory (MP2), and the Ha rtree-Fock-Slater (HFS) method are compared. Atomic charges, dipole mo ments, topological properties of the electron density distribution and polarizabilities, and first hyperpolarizabilities are calculated. Ato mic charges obtained with the HFS method are found to be very close to those calculated with the MP2 method, from which we conlcude that the HFS method describes to some extent electron correlation effects. Per forming an MP2 calculation after an HF calculation improves the molecu lar dipole moments considerably, yielding values close to the experime ntal ones. HFS calculations are computationally less demanding than MP 2 and yield comparable results for the electron density distributions, dipole moments and polarizabilities.